A great little apartment right in the heart of downtown Cologne. This place is walking distance from everything, and across the street from the famous Dom cathedral. I stayed here for a week and it was just right.
This is not your typical hotel, and it might not be for everyone. Don't book here if you want room service, daily cleanings, an attached spa, or hotel staff to hold your hand throughout your trip. Proceed with caution if you don't speak the language - there's no front desk, so check-in is at the kebab place next door and can get confusing.
But if you're the independent type that wants a home base to return to after a day of exploring this exciting and historic city, I cannot recommend First Domizil highly enough.